Among the uncharacterized factors in crude human chorionic gonadotropin (hCG), an extract of pregnancy urine, are two which effect immunological functions: the previously described immunosuppressive factor and a new immunoenhancing factor. Preliminary data show that the immunoenhancing factor, called pregnancy associated growth factor (PAGF) is a mitogen for normal human peripheral blood lymphocytes (PBL) in fetal calf serum (FCS). PAGF causes T cells, probably confined to the helper or inducer subclass, to proliferate in the presence of an Ia+ non-T cell. PAGF (MW 18-24,000), and the immunosuppressive (MW 40,000) are easily separable chromatographically so that each can be evaluated independently of the other. This proposal concentrates on the purification of PAGF; the production of anti-PAGF antibodies and the development of an immunoassay for PAGF. To assess the biological role of PAGF, it will be evaluated in lymphoproliferative and other assays of immune function such as in vitro generation of suppressor cells and antibody formation. PAGF will also be evaluated as growth factor for non-lymphoid cells. The results of this proposal should help to define whether PAGF is a normal growth factor or mitogen, present in normal urine or pregnancy "unique"; whether it is specific for immunocompetent cells or has broader cell specificity; and whether it is related to previously described immunological and non-immunological growth factors. The immunoassay will initially quantitate PAGF in the blood and urine of normal and pregnant individuals. If promising PAGF will be measured in certain disease states such as autoimmunity, neoplasia and immunodeficiency. In addition, crude hCG may provide an unappreciated, underutilized source of uncharacterized growth factors necessary for fetal development and/or differentiation.